Pressure relief in a respiratory assistance system

ABSTRACT

A pressure relief device comprising a valve configured to resiliently deform in response to a predetermined pressure; and a sound dampener configured to dampen a sound generated by the valve when the valve resiliently deforms in response to said predetermined pressure.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/359,773, filed Jan. 27, 2012, entitled “PRESSURE RELIEF IN ARESPIRATORY ASSISTANCE SYSTEM,” that claims priority to and benefit ofU.S. Provisional Patent Application Ser. No. 61/437,479, filed Jan. 28,2011, entitled “PRESSURE-LIMITED VARIABLE-FLOW NASAL CPAP SYSTEM,” thedisclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

Breathing assistance systems are utilized to treat patients experiencingrespiratory difficulties and/or insufficiencies. In some instances, thegas source for such systems may generate elevated pressures above adesired pressure threshold. As a result, the elevated pressures canresult in barotrauma to the patient.

Moreover, some devices within the breathing assistance systems cangenerate loud sounds during operation. As a result, the loud sounds mayirritate or harm the patients (e.g., neonates).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a respiratory assistance system.

FIG. 2 illustrates an embodiment of a respiratory assistance system.

FIG. 3 illustrates an embodiment of a pressure relief device.

FIGS. 4A-E illustrates embodiments of a sound dampener.

The drawings referred to in this description should be understood as notbeing drawn to scale except if specifically noted.

DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to embodiments of the presenttechnology, examples of which are illustrated in the accompanyingdrawings. While the technology will be described in conjunction withvarious embodiment(s), it will be understood that they are not intendedto limit the present technology to these embodiments. On the contrary,the present technology is intended to cover alternatives, modificationsand equivalents, which may be included within the spirit and scope ofthe various embodiments as defined by the appended claims.

Furthermore, in the following description of embodiments, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present technology. However, the present technologymay be practiced without these specific details. In other instances,well known methods, procedures, components, and circuits have not beendescribed in detail as not to unnecessarily obscure aspects of thepresent embodiments.

FIG. 1 depicts an embodiment of respiratory assistance system 100.System 100 can be any respiratory system that generates a gas source forrespiratory assistance. Such systems (e.g., invasive or non-invasive)can be, but are not limited to, a ventilator system, a continuouspositive airway pressure (CPAP) system, a nasal CPAP (nCPAP) system, apressure limited variable flow nCPAP system, etc.

System 100 includes pressure relief device 110, patient interface 120and gas source 130. Relief device 110, patient interface 120 and gassource 130 are fluidly connected with one another via tubing.

Patient interface 120 can be, but is not limited to, a single limbinterface, a double limb interface, a CPAP generator, etc.

Gas source 130 can be, but is not limited to, a flow driver for a CPAPsystem, a ventilator for a ventilator system, etc.

It should be appreciated that the flow driver provides a CPAP generatorwith a flow of gas. The CPAP generator receives the flow of gas (e.g.,air and/or oxygen) and subsequently generates a CPAP to be delivered tothe patient. The CPAP can be generated by various physical featureswithin the generator, such as but not limited to contours, jets, etc.Typically, flow drivers in a CPAP system operate at higher pressuresthan the operating pressures of a ventilator system.

In general, in a ventilator system, the requisite air flow and pressureis mechanically generated at the ventilator. The requisite airflow isthen delivered to the patient via a patient interface.

Pressure relief device 110 is any pressure relief device that relievespressure in system 100. In particular, pressure relief device 110ensures that a pressure in system 100 does not exceed a predeterminedpressure. For example; a patient receives a first pressure of gas atpatient interface 120 for respiratory assistance. Gas source 130generates a second pressure of gas which is greater than the firstpressure. If the patient receives the second pressure of gas, thenbarotrauma may result. However, pressure relief device 110, in responseto the second pressure, relieves or vents gas from system 100 such thatthe patient does not receive the second pressure. In one embodiment,pressure relief device 110 vents gas from system 100 such that thepressure in system 100 is the prescribed pressure for the patient.

In one embodiment, pressure relief device 110 disposed in the source gasline (as depicted in FIG. 1). In another embodiment, pressure reliefdevice 110 is disposed proximate, or integral with patient interface120. In a further embodiment, pressure relief device 110 is disposedproximate, or integral with gas source 130.

In one embodiment, pressure relief device 110 is an umbrella valvedevice, such as pressure relief device 310, as depicted in FIG. 3. Adetailed description of pressure relief device 310 is provided below.

FIG. 2 depicts an embodiment of respiratory assistance system 200. Inparticular, system 200 is a CPAP system. In various embodiments; theCPAP system is pressure-limited variable-flow CPAP (or nCPAP) system.

Conventional variable flow CPAP systems typically utilize asubstantially higher drive pressure, for example, in excess of 200cmH2O, to create CPAP pressures of up to 20 cmH2O. In contrast, system200 (e.g.; a pressure-limited CPAP system) utilizes lower drivepressure, for example 60 cmH2O, to create CPAP pressures up to 20 cmH2O.

A “variable flow” system, in general, allows for some degree of controlof gas flow and/or oxygen concentration of the CPAP system. In contrast,a fixed (or non-variable flow) CPAP system does not allow for control ofgas flow and/or oxygen concentration.

System 200 includes a gas source 230 (e.g., a flow driver) that providesgas to CPAP device 270. In particular, generator body 250 receives thegas from gas source 230. Generator body 250 receives the flow of gas(e.g., air and/or oxygen) and subsequently generates a CPAP to bedelivered to the patient. The CPAP can be generated by various physicalfeatures within the generator body 250, such as but not limited tocontours, jets, etc.

The CPAP is received by the patient via patient interface 220. When thepatient exhales, the exhalation is passes through patient interface 220,generator body 250 and exits system 200 at ambient tubing 260.

In one embodiment, system 200 includes pressure monitor 240 configuredto monitor pressure in system 200.

It should be appreciated that variable-flow nCPAP devices (e.g., InfantFlow nCPAP, Airlife nCPAP) are traditionally operated by connecting to aflow-driving device. These devices operate at drive pressuressignificantly higher than devices used for ventilation purposes. Inorder to utilize a variable-flow device on a ventilator platform, thedrive pressure must be reduced significantly.

Conventional CPAP flow-driving devices are compatible with low-drivepressure nCPAP systems, such as CPAP device 270 when the flow driver isfunctional and monitoring the patient pressure. However, flow driversthat have the ability to administer flow without monitoring (e.g.,Infant Flow SiPAP, P-Driver) rely on drive pressure to trigger a reliefmechanism, by the flow-driving device when the monitoring is turned off.A typical relief mechanism is a spring loaded mechanical relief valvewhich operates at pressures above 200 cmH2O, integrated within the CPAPdriver, and suitable for multi-patient use.

In contrast, pressure relief device 210 is a disposable device. In oneembodiment, pressure relief device operates at pressures above 60 cmH2O.In another embodiment, pressure relief device 210 is reusable for singlepatient use.

When using a variable-flow CPAP system, such as system 200, whichrequires less drive pressure to obtain the same patient pressure,increasing the drive pressure to levels deemed acceptable for older,high-drive pressure variable-flow systems would result in much higherpressure seen by the patient when no monitoring occurs. This couldresult in barotrauma to the patient. Incorporating a pressure-reliefmechanism (e.g.; pressure relief device 210) would ensure that thisscenario of high patient pressures as a result of unmonitored high drivepressures on a flow driver device would not cause unwanted highpressures to be seen by the patient.

Therefore, incorporating a pressure-relief system (e.g., pressure reliefdevice 210) that vents at a desired pressure (can be related to both thedrive or patient pressure) allows for the variable-flow nCPAP device(e.g., system 200) to be used safely on both an old flow-driving device,as well as, have low-enough drive pressure for compatibility withventilator platforms.

In one embodiment, pressure relief device 210 is disposed in the sourcegas line (as depicted in FIG. 2). In another embodiment, pressure reliefdevice 210 is disposed proximate, or integral with CPAP device 270 andin particular, with generator body 250. In a further embodiment,pressure relief device 210 is disposed proximate, or integral with gassource 230.

FIG. 3 depicts an embodiment of a pressure relief device 310. Pressurerelief device 310 is an umbrella relief device. In particular, pressurerelief device 310 includes umbrella valve 320 and sound dampener 330disposed in housing 340. For example, sound dampener 330 is disposedbetween lid 350 and umbrella valve 320.

Umbrella valve 320 is configured to unseal with housing 340 at apredetermined pressure. For example, umbrella valve 320 is sealed withthe interior of housing 340 at a first pressure, such that airflowpasses through tubes 361 and 360. For instance, at the first pressure,umbrella valve 320 is sealed such that air flow is effectively deliveredfrom a gas source to a patient interface. It should be appreciated thatair flow can flow in the direction of tube 360 to tube 361 or in thedirection from tube 361 to tube 360.

However, if pressure in the system increases to a predetermined pressure(higher than the first pressure), then umbrella valve resilientlydeforms to allow gas flow to pass out of a plurality of vents in housing340 to relieve the pressure in the system. The predetermined pressure isalso known as the cracking, opening or relieving pressure.

Umbrella valve 320 generates a high noise level (e.g., 80-85 db) when itdeforms in response to the predetermined pressure. This high noise levelcan irritate patients, especially those with sensitive hearing, such asneonates. In some instances, the generated high noise level may harm thehearing of the patient.

However, sound dampener 330 dampens the noise level generated byumbrella valve 320. For example, as umbrella valve 320 deforms, itphysically contacts sound dampener 330. In one embodiment, when therelief valve is activated, the sound generated by umbrella valve 320 isreduced to 50 db or less.

In one embodiment, the sound is reduced at a prescribed range of around≦35 liters per minute (LPM) drive flow. In another embodiment, the soundis reduced at a prescribed range of around ≦20 LPM drive flow.

Sound dampener 330 can be any material that facilitates in dampening thesound generated by umbrella valve 320. In one embodiment, sound dampener330 is polyurethane foam. In various embodiments, sound dampener 330 canbe, but is not limited to, felt, cloth, any perforated material, etc.

Sound dampener 330 can be die cut or laser cut. It should be appreciatedthat the edges of sound dampener are straight. In other words, the edgesof the sound damper have no or very limited roundness or taper.

Sound dampener 330 also reduces the standard deviation the crackingpressure of umbrella valve 320. For example, umbrella valve 320 deformsor cracks between 50 and 70 cc H₂O, when sound dampener is not utilized.However, when sound dampener 330 is utilized, the standard deviation ofthe cracking pressure is narrowed such that the umbrella valve 320consistently cracks on or around 60 ccH₂O.

FIGS. 4A-E depicts embodiments of sound dampeners 430A-E, respectively.FIG. 4A depicts sound dampener 430A with a pin wheel shape. In oneembodiment, sound dampener 430A includes centering feature 440configured to facilitate in the centering of sound dampener 430A withinhousing 340. Centering feature 440 can be any shape that is compatiblefor centering. For example, centering feature 440 can be, but is notlimited, to a hole, void, indentation, bulge, ridge, ring, peg(s) orpost(s), etc. In another embodiment, centering feature 440 correspondswith a centering feature on lid 350.

FIG. 4B depicts sound dampener 430B with a pin wheel shape. FIG. 4Cdepicts sound dampener 430C with a clover leaf shape. FIG. 4D depictssound dampener 430D with a disk shape. FIG. 4E depicts sound dampener430E with a ring shape. It should be appreciated that the depictedshapes are not limiting or exhaustive. As such, the sound dampener canbe any shape that is able to dampen sound of umbrella valve 320.

Various embodiments are thus described. While particular embodimentshave been described, it should be appreciated that the embodimentsshould not be construed as limited by such description, but ratherconstrued according to the following claims.

1. A method of controlling fluid pressure through a pressure relief device, the method comprising: connecting the pressure relief device to a respiratory assistance system, the pressure relief device comprising a housing having a vent, a first tube, and a second tube fluidly coupled within the housing, the vent defining a passage from within the housing to an ambient environment; retaining a valve within the housing to obstruct the vent, the valve being retained between the vent, the first tube, and the second tube; and resiliently deforming said valve, in response to a predetermined pressure in the respiratory assistance system, to (i) fluidly couple the vent, the first tube, and the second tube, and (ii) contact a sound dampener to dampen a sound generated by said valve when said valve resiliently deforms.
 2. The method of claim 1, further comprising connecting the pressure relief device between a gas source and a patient interface.
 3. The method of claim 1, further comprising sealing the valve with the housing at a first pressure so that a flow passes through the first tube and the second tube.
 4. The method of claim 1, wherein said valve is an umbrella valve.
 5. The method of claim 1, wherein the predetermined pressure is greater than the first pressure.
 6. The method of claim 1, further comprising providing a lid coupled to the housing, wherein said sound dampener is disposed between said lid and said valve.
 7. The method of claim 1, further comprising centering said sound dampener within said housing with a centering feature of said sound dampener.
 8. The method of claim 7, further comprising centering said sound dampener with a corresponding centering feature of a lid coupled to the housing.
 9. The method of claim 1, wherein a shape of said sound dampener is selected from a group consisting of: a disk shape, a ring shape, a clover-like shape, and a pinwheel-like shape.
 10. The method of claim 1, wherein said respiratory assistance system is a continuous positive airway pressure (CPAP) system.
 11. The method of claim 1, wherein said respiratory assistance system is a nasal continuous positive airway pressure (nCPAP) system.
 12. The method of claim 1, wherein said patient interface comprises a CPAP generator.
 13. The method of claim 1, wherein said patient interface comprises an nCPAP generator.
 14. The method of claim 1, wherein said first tube and said second tube are collinear.
 15. The method of claim 1, wherein said first tube and said second tube are fluidly coupled when said valve is not deformed.
 16. A method of controlling fluid pressure in a variable-flow continuous positive airway pressure (CPAP) system, the method comprising: connecting a pressure relief device between a flow driver and a CPAP generator, the pressure relief device comprising a housing having a vent, a first tube, and a second tube fluidly coupled within the housing, the vent defining a passage from within the housing to an ambient environment; retaining a valve within the housing to obstruct the vent, the valve being retained between the vent, the first tube, and the second tube; and resiliently deforming said valve, in response to a predetermined pressure in the variable-flow CPAP system, to (i) fluidly couple the vent, the first tube, and the second tube, and (ii) contact a sound dampener to dampen a sound generated by said valve when said valve resiliently deforms.
 17. The method of claim 16, further comprising sealing the valve with the housing at a first pressure so that a flow passes through the first tube and the second tube.
 18. The method of claim 16, wherein said valve is an umbrella valve.
 19. The method of claim 16, wherein the predetermined pressure is greater than the first pressure.
 20. The method of claim 16, wherein a shape of said sound dampener is selected from a group consisting of: a disk shape, a ring shape, a clover-like shape, and a pinwheel-like shape. 